Washers are frequently used to clean articles used in the care of laboratory animals, such as animal cages (e.g., wire cages and plastic boxes), racks, debris pans, watering devices, bottles, and feeder bowls. These articles are often heavily soiled with solid debris (including, but not limited to, residues and dirt) from bedding, foodstuffs and animal wastes. One type of washer widely used for cleaning such articles are tunnel washers. Tunnel washers are typically divided into a plurality of processing chambers, wherein pre-washing, washing, rinsing and drying operations are respectively performed. During the pre-washing, washing and rinsing operations various fluids, including, but not limited to, water and water vapor, are introduced and removed from the respective chambers. During drying operations, heated air is circulated through a drying chamber to dry the article.
The process for removing dirt and debris begins in the pre-washing chamber, where spray jets or nozzles are used to spray hot water onto the article. Water sprayed into the pre-washing chamber is collected in a sump, and removed from the tunnel washer through a drain.
In order to conserve water and improve efficiency, it is advantageous to re-use at least some of the water collected in the sump by recirculating the used water back into the pre-washing chamber through the washer nozzles. Since the articles are typically heavily soiled when passing through the pre-washing chamber, the water collected in the sump may contain solid debris large enough to clog the washer nozzles. Therefore, before the water collected by the sump can be re-used the water must pass through a filter to remove solid debris that could cause the washer nozzles to become clogged. In order to maintain effective operation of this filter, periodic filter cleaning is necessary.
Existing filters have numerous drawbacks. In this regard, existing filters require frequent cleaning operations (e.g., backflushing) in order to maintain effective operation of the filter. Other problems with existing filters are the cost and complexity of devices (e.g., motors and/or blades) needed to carry out filter cleaning operations. The present invention addresses these and other drawbacks of existing filters.